Fig. 2.

STAU2 is a target of caspase(s). Cells were incubated in the presence of different peptidase inhibitors as indicated or DMSO (vehicle). Cell extracts were analyzed by Western blotting for STAU2 expression. All Western blots are representative of at least three independently performed experiments that gave similar results. Quantification of STAU2 protein levels is indicated below the gels. The ratio of STAU2 on the loading control in DMSO-treated cells was fixed to 1. * p-value ≤0.05; ** p-value ≤0.01. One sample t-test. PARP1 was used as a measure of caspase inhibition. a, b hTERT-RPE1 and HCT116 cells were incubated in the presence of the proteasome inhibitor MG132 (10 μM) for 6 h (a) or the lysosome inhibitor iLYS (10 μM) for 10 h (b). c hTERT-RPE1 (top) and HCT116 (bottom) cells were incubated in the presence of caspase inhibitors: ZVAD-FMK (50 μM for 0, 8, 12, 24 h) or emricasan (40 μM for 24 h). d HCT116 cells were transfected with a plasmid coding for STAU2⁵⁹-FLAG₃. Cells were then incubated in the presence of DMSO (−) or of the caspase inhibitor Emricasan (40 μM) (+) for 24 h. Full length and degradation fragments were visualized by anti-STAU2 and anti-FLAG antibodies to detect the N- and C-terminal ends of STAU2, respectively. Western blots are representative of two independently performed experiments. β-actin was used as a loading control. (bottom) Schematic representation of STAU2 protein. Predicted caspase cleavage sites are shown. Red and blue boxes: major and minor RNA-binding domains, respectively. Black boxes, regions with RNA-binding consensus sequence but lacking RNA-binding activity in vitro. Hatched boxes, tubulin-binding domain